Terminal Services Disconnects Second User at the Same Remote Location

We have several remote locations that connect to a server running
Windows 2003. The server has licensing for 25 client users and 10
terminal services users. The workstations are running everything from
W98 to W2K to WXP. These locations are all using DSL for
communications. It appears that one user from each location can logon
without any problem, however if a second user tries to logon from the
same remote location it disconnects the current user at that location
or will not allow the second user to logon. Ususally an icon appears
in the upper right corner of the screen which depicts two networked
terminals with a red X on the network connection.

We've tried everything we can think of, but nothing seems to help. Any
assistance would be greatly appreciated.

Thanks,
John